Reactions of arsenate [As(V)] in a single nanoscale zero-valent iron (nZVI) particle are mapped by spherical aberration-corrected scanning transmission electron microscopy integrated with X-ray energy dispersive spectroscopy. Near-atomic-resolution distributions of arsenic, iron, and oxygen demonstrate the diffusion and reactions of arsenic in nZVI. The reactions occur primarily in the surface layer, especially at the oxide−metallic iron [Fe(0)] interface. As(V) is attracted to the surface via electrostatic interactions and embedded in the nanoparticle via chemical reduction to form a thin (1.0−1.2 nm) layer of elemental arsenic inside the shell. Results offer unprecedented details about the intraparticle reaction mechanisms and demonstrate intrinsic advantages of nZVI for arsenic encapsulation, treatment, and remediation.

Sequestration of arsenate in zero-valent iron nanoparticles: Visualization of intraparticle reactions at Angstrom resolution

249th National Meeting (2015)

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